github.com/jingcheng-WU/gonum@v0.9.1-0.20210323123734-f1a2a11a8f7b/mat/format_example_test.go (about)

     1  // Copyright ©2015 The Gonum Authors. All rights reserved.
     2  // Use of this source code is governed by a BSD-style
     3  // license that can be found in the LICENSE file.
     4  
     5  package mat_test
     6  
     7  import (
     8  	"fmt"
     9  
    10  	"github.com/jingcheng-WU/gonum/mat"
    11  )
    12  
    13  func ExampleFormatted() {
    14  	a := mat.NewDense(3, 3, []float64{1, 2, 3, 0, 4, 5, 0, 0, 6})
    15  
    16  	// Create a matrix formatting value with a prefix and calculating each column
    17  	// width individually...
    18  	fa := mat.Formatted(a, mat.Prefix("    "), mat.Squeeze())
    19  
    20  	// and then print with and without zero value elements.
    21  	fmt.Printf("with all values:\na = %v\n\n", fa)
    22  	fmt.Printf("with only non-zero values:\na = % v\n\n", fa)
    23  
    24  	// Modify the matrix...
    25  	a.Set(0, 2, 0)
    26  
    27  	// and print it without zero value elements.
    28  	fmt.Printf("after modification with only non-zero values:\na = % v\n\n", fa)
    29  
    30  	// Modify the matrix again...
    31  	a.Set(0, 2, 123.456)
    32  
    33  	// and print it using scientific notation for large exponents.
    34  	fmt.Printf("after modification with scientific notation:\na = %.2g\n\n", fa)
    35  	// See golang.org/pkg/fmt/ floating-point verbs for a comprehensive list.
    36  
    37  	// Output:
    38  	// with all values:
    39  	// a = ⎡1  2  3⎤
    40  	//     ⎢0  4  5⎥
    41  	//     ⎣0  0  6⎦
    42  	//
    43  	// with only non-zero values:
    44  	// a = ⎡1  2  3⎤
    45  	//     ⎢.  4  5⎥
    46  	//     ⎣.  .  6⎦
    47  	//
    48  	// after modification with only non-zero values:
    49  	// a = ⎡1  2  .⎤
    50  	//     ⎢.  4  5⎥
    51  	//     ⎣.  .  6⎦
    52  	//
    53  	// after modification with scientific notation:
    54  	// a = ⎡1  2  1.2e+02⎤
    55  	//     ⎢0  4        5⎥
    56  	//     ⎣0  0        6⎦
    57  }
    58  
    59  func ExampleFormatted_mATLAB() {
    60  	a := mat.NewDense(3, 3, []float64{1, 2, 3, 0, 4, 5, 0, 0, 6})
    61  
    62  	// Create a matrix formatting value using MATLAB format...
    63  	fa := mat.Formatted(a, mat.FormatMATLAB())
    64  
    65  	// and then print with and without layout formatting.
    66  	fmt.Printf("standard syntax:\na = %v\n\n", fa)
    67  	fmt.Printf("layout syntax:\na = %#v\n\n", fa)
    68  
    69  	// Output:
    70  	// standard syntax:
    71  	// a = [1 2 3; 0 4 5; 0 0 6]
    72  	//
    73  	// layout syntax:
    74  	// a = [
    75  	//  1 2 3
    76  	//  0 4 5
    77  	//  0 0 6
    78  	// ]
    79  }
    80  
    81  func ExampleFormatted_python() {
    82  	a := mat.NewDense(3, 3, []float64{1, 2, 3, 0, 4, 5, 0, 0, 6})
    83  
    84  	// Create a matrix formatting value with a prefix using Python format...
    85  	fa := mat.Formatted(a, mat.Prefix("    "), mat.FormatPython())
    86  
    87  	// and then print with and without layout formatting.
    88  	fmt.Printf("standard syntax:\na = %v\n\n", fa)
    89  	fmt.Printf("layout syntax:\na = %#v\n\n", fa)
    90  
    91  	// Output:
    92  	// standard syntax:
    93  	// a = [[1, 2, 3], [0, 4, 5], [0, 0, 6]]
    94  	//
    95  	// layout syntax:
    96  	// a = [[1, 2, 3],
    97  	//      [0, 4, 5],
    98  	//      [0, 0, 6]]
    99  }
   100  
   101  func ExampleExcerpt() {
   102  	// Excerpt allows diagnostic display of very large
   103  	// matrices and vectors.
   104  
   105  	// The big matrix is too large to properly print...
   106  	big := mat.NewDense(100, 100, nil)
   107  	for i := 0; i < 100; i++ {
   108  		big.Set(i, i, 1)
   109  	}
   110  
   111  	// so only print corner excerpts of the matrix.
   112  	fmt.Printf("excerpt big identity matrix: %v\n\n",
   113  		mat.Formatted(big, mat.Prefix(" "), mat.Excerpt(3)))
   114  
   115  	// The long vector is also too large, ...
   116  	long := mat.NewVecDense(100, nil)
   117  	for i := 0; i < 100; i++ {
   118  		long.SetVec(i, float64(i))
   119  	}
   120  
   121  	// ... so print end excerpts of the vector,
   122  	fmt.Printf("excerpt long column vector: %v\n\n",
   123  		mat.Formatted(long, mat.Prefix(" "), mat.Excerpt(3)))
   124  	// or its transpose.
   125  	fmt.Printf("excerpt long row vector: %v\n",
   126  		mat.Formatted(long.T(), mat.Prefix(" "), mat.Excerpt(3)))
   127  
   128  	// Output:
   129  	// excerpt big identity matrix: Dims(100, 100)
   130  	//  ⎡1  0  0  ...  ...  0  0  0⎤
   131  	//  ⎢0  1  0            0  0  0⎥
   132  	//  ⎢0  0  1            0  0  0⎥
   133  	//   .
   134  	//   .
   135  	//   .
   136  	//  ⎢0  0  0            1  0  0⎥
   137  	//  ⎢0  0  0            0  1  0⎥
   138  	//  ⎣0  0  0  ...  ...  0  0  1⎦
   139  	//
   140  	// excerpt long column vector: Dims(100, 1)
   141  	//  ⎡ 0⎤
   142  	//  ⎢ 1⎥
   143  	//  ⎢ 2⎥
   144  	//   .
   145  	//   .
   146  	//   .
   147  	//  ⎢97⎥
   148  	//  ⎢98⎥
   149  	//  ⎣99⎦
   150  	//
   151  	// excerpt long row vector: Dims(1, 100)
   152  	//  [ 0   1   2  ...  ...  97  98  99]
   153  }